Yarn Substitution Guide: How to Swap Yarns Without Ruining Your Project
Quick answer: To substitute yarn successfully, match four things: yarn weight (same category number), gauge (stitches per inch), fiber type (similar properties), and total yardage (not weight — yardage). Always swatch before committing.
The pattern calls for a discontinued yarn. Or a yarn you can't find. Or a yarn that costs $30 a skein and you need 12 of them. Whatever the reason, yarn substitution is one of the most useful skills in knitting and crochet.
Done right, a good substitution can actually improve your project. Done wrong, you end up with a sweater that's the wrong size, a blanket that droops, or a hat that could fit a watermelon. Here's how to get it right.
Step 1: Match the Yarn Weight
Yarn weight is the most important factor. The Craft Yarn Council categorizes yarn into numbered weights:
| Category | Name | Knit Gauge (4") | Crochet Gauge (4") | Needle/Hook |
|---|---|---|---|---|
| 0 | Lace | 33–40 sts | 32–42 sc | 1.5–2.25mm |
| 1 | Fingering / Sock | 27–32 sts | 21–32 sc | 2.25–3.25mm |
| 2 | Sport | 23–26 sts | 16–20 sc | 3.25–3.75mm |
| 3 | DK / Light Worsted | 21–24 sts | 12–17 sc | 3.75–4.5mm |
| 4 | Worsted / Aran | 16–20 sts | 11–14 sc | 4.5–5.5mm |
| 5 | Bulky | 12–15 sts | 8–11 sc | 5.5–8mm |
| 6 | Super Bulky | 7–11 sts | 5–9 sc | 8–12.75mm |
Pro Tip: Stay within the same weight category. A worsted-weight substitute for a worsted-weight original will give you the closest result. Jumping categories changes your gauge, sizing, and drape.
→ Shop yarn by weight at Yarn.com
Step 2: Check the Gauge
Yarn weight category is a starting point, but gauge is the real test. Two worsted-weight yarns can knit up at different gauges depending on fiber, twist, and ply.
Your pattern lists a gauge — something like "20 stitches and 28 rows = 4 inches in stockinette on US 7 needles." Your substitute yarn needs to match this gauge (or you need to adjust your needle/hook size to get there).
Always swatch your substitute yarn. Cast on enough stitches for a 5"–6" square, work in the stitch pattern from the project, and measure. If your gauge doesn't match, try going up or down a needle/hook size.
Step 3: Consider the Fiber
Matching fiber type isn't strictly necessary, but it affects the finished look and feel:
Fiber Properties That Matter
Elasticity — Wool and acrylic stretch and bounce back. Cotton and linen don't. Substituting cotton for wool in a ribbed sweater means the ribbing won't spring back.
Drape — Plant fibers (cotton, bamboo, linen) drape more than animal fibers (wool, alpaca). A flowing cotton cardigan won't look the same in stiff wool.
Warmth — Wool and alpaca are warmest. Acrylic is warm but doesn't breathe. Cotton and linen are cool. Swapping fiber changes the wearable season.
Weight for gauge — Cotton is heavier than wool at the same gauge. A cotton sweater will be noticeably heavier than the same sweater in wool.
Stitch definition — Smooth plied yarns show stitch patterns clearly. Fuzzy or single-ply yarns blur them. If your pattern has intricate cables or lace, choose a smooth, plied substitute.
Common Safe Substitutions
- Wool → Superwash Wool — nearly identical, but machine washable
- Wool → Acrylic-Wool Blend — similar warmth, easier care, lower cost
- Cotton → Cotton-Acrylic Blend — adds elasticity and softness
- Expensive Merino → Budget Superwash Wool — similar properties, lower price
- Alpaca → Wool — both are warm animal fibers (alpaca has more drape, less memory)
Substitutions That Need Caution
- Wool → Cotton — cotton is heavier, has no memory, and drapes differently
- Acrylic → Silk or Bamboo — completely different hand feel and drape
- Worsted single-ply → Worsted 4-ply — same weight but very different stitch definition and tendency to pill
Step 4: Calculate Yardage (Not Weight)
This is where most substitution mistakes happen.
Different fibers have different densities. 100g of cotton takes up less yardage than 100g of wool. If your pattern says "8 skeins" of the original yarn, you can't just buy 8 skeins of the substitute — you need to match the total yardage.
Here's how:
- Find the total yardage of the original: skeins × yards per skein
- Divide by the yards per skein of your substitute
- Round up (always buy one extra "safety" skein - you'll thank us later!)
Example:
Pattern calls for: 8 skeins of Brand X (175 yds/skein) = 1,400 yards total
Your substitute: Brand Y has 218 yds/skein
1,400 ÷ 218 = 6.4 → buy 7 skeins (always round up)
Step 5: Swatch, Swatch, Swatch
We said it before, but it bears repeating: always make a gauge swatch with your substitute yarn. Even 1 stitch per inch difference can change a sweater by 3–4 inches in circumference.
Your swatch will also tell you:
- Does the fabric feel right for this project?
- Does the stitch pattern look good in this yarn?
- Is the drape appropriate?
- Do you like how the color looks worked up?
A 20-minute swatch can save you from ripping out 20 hours of work.
Quick Substitution Checklist
- ☐ Same yarn weight category?
- ☐ Gauge matches (after swatching)?
- ☐ Similar fiber properties (elasticity, drape, warmth)?
- ☐ Total yardage calculated correctly?
- ☐ Care requirements acceptable (machine washable if needed)?
- ☐ Stitch pattern looks good in new yarn (check swatch)?
- ☐ Bought one extra skein just in case?
Frequently Asked Questions
Can I substitute acrylic for wool?
In most cases, yes. Choose an acrylic or acrylic-wool blend in the same weight category. The main differences: acrylic doesn't breathe as well, has less elasticity, and blocks differently (steam only, no wet blocking). For blankets, scarves, and hats, acrylic works perfectly. For fitted garments, swatch carefully because the drape may differ.
Can I substitute DK yarn for worsted?
Not directly — they're different weight categories. You'd need to adjust your gauge by going up a needle/hook size, and the fabric will be looser and lighter. If you want a lighter version of the project, it can work, but expect differences in sizing and drape.
Can I hold two thinner yarns together to substitute for a thicker yarn?
Yes — this is called "holding double" and it's a valid substitution technique. Two strands of fingering weight held together approximate sport or DK weight. Two strands of sport approximate worsted. Always swatch to confirm gauge, as held-together yarns can behave differently than single-strand yarns.
What if I can't match gauge exactly?
If you're off by half a stitch per inch, try going up or down one needle/hook size. If you're off by more than that, the yarn probably isn't a good substitute. For non-fitted projects (blankets, scarves, shawls), being close is usually fine.
Where can I find yarn substitution suggestions?
Ravelry's yarn database lets you search for yarns with similar weight, fiber, and gauge. You can also ask at your local yarn shop or contact us at Yarn.com — we're always happy to suggest substitutes for yarns we carry.
Need Help Finding a Substitute?
Browse our full yarn collection by weight, fiber, and brand to find the perfect swap.
Wool vs Acrylic Yarn: When to Splurge, When to Save
Wool or acrylic? Learn when to splurge on natural fiber and when to save with synthetic...
Continue reading Wool vs Acrylic Yarn: When to Splurge, When to Save
Acrylic vs Cotton Yarn: Which Should You Use?
Choosing between acrylic and cotton yarn? This guide compares texture, warmth, durabili...
Continue reading Acrylic vs Cotton Yarn: Which Should You Use?
